Culturable fish seeds in Nigerian waters: A research survey (1978-1985)

The desired species identified in this survey include mullets, catfishes, fast growing fish predators, species for control of weeds and grass it, ponds, cichlids and shrimps. Five coastal states: Lagos, Ondo, Bendel, Rivers, and Cross River were covered in the studies. Investigations were also carried into the major rivers and their tributaries. A combination of the estimation methods of Le Cren, (1962) and Pitcher and Mac Donald (1973) was employed in the analysis of data. From the detailed data collected from (1978-1985), the survey indicated that about 100 million fish seeds can be collected annually from Nigerian waters using appropriate gear-seine nets, cast nets, and fish traps. Of this number, 60% is available along the coastal belt of the country while 40% is in the major rivers, their tributaries and swamps. At the present level of fish culture development in Nigeria, this is more than enough, even after allowing for 50% mortality due to handling and transportation stress

Effects of extracts of dried seeds of Toloache, Datura innoxia as anaesthesia on the African catfish Clarias gariepinus fingerlings

The effects of crude extract, pure extract, aqueous, fraction of pure and lipid fraction of pure extract of dried seeds of toloache. Datura innoxia as anaesthesia on the African catfish. Clarias gariepinus fingerlings were studied. The fish were exposed to various doses of the extract in aquaria tanks and the time taken for each fish to reach anaesthesia was recorded. The fish were anaesthetized up to 3.00g/l fingerlings reached anaesthesia is significantly (P<0.05) shorter time (1.004 minutes at 0.05gl) in pure unseparated extract than in crude extract (58.50 minutes at 3.00g/l concentrated). The time to reach anaesthesia decreased with an increase in concentration of the seed extract. Out the two fractions the lipid fraction had significantly (P>0.05) better anaesthetic on the fish. The control produced no observable anaesthetic effect on the fish within three hours. This suggests that the anaesthetizing active ingredent resided in the lipid fraction. All fish recovered from anaesthesia, swam and fed actively and no mortality was observed throughout the exposure period and thereafter. It is therefore recommended for use on C. gariepinus fingerlings